/*********************************************************************
*
*      Copyright (C) 2005 Andrew Khan
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
***************************************************************************/

package jxl.biff;

/**
 * A growable array of bytes
 */
public class ByteArray {
	
	/**
	 * The array grow size
	 */
	private int growSize;

	/**
	 * The current array
	 */
	private byte[] bytes;

	/**
	 * The current position
	 */
	private int pos;

	// The default grow size
	private final static int defaultGrowSize = 1024;

	/**
	 * Constructor
	 */
	public ByteArray() {
		this(defaultGrowSize);
	}

	/**
	 * Constructor
	 *
	 * @param gs
	 */
	public ByteArray(int gs) {
		growSize = gs;
		bytes = new byte[defaultGrowSize];
		pos = 0;
	}

	/**
	 * Adds a byte onto the array
	 *
	 * @param b
	 *            the byte
	 */
	public void add(byte b) {
		checkSize(1);
		bytes[pos] = b;
		pos++;
	}

	/**
	 * Adds an array of bytes onto the array
	 *
	 * @param b
	 *            the array of bytes
	 */
	public void add(byte[] b) {
		checkSize(b.length);
		System.arraycopy(b, 0, bytes, pos, b.length);
		pos += b.length;
	}

	/**
	 * Gets the complete array
	 *
	 * @return the array
	 */
	public byte[] getBytes() {
		byte[] returnArray = new byte[pos];
		System.arraycopy(bytes, 0, returnArray, 0, pos);
		return returnArray;
	}

	/**
	 * Checks to see if there is sufficient space left on the array. If not,
	 * then it grows the array
	 *
	 * @param sz
	 *            the amount of bytes to add
	 */
	private void checkSize(int sz) {
		while (pos + sz >= bytes.length) {
			// Grow the array
			byte[] newArray = new byte[bytes.length + growSize];
			System.arraycopy(bytes, 0, newArray, 0, pos);
			bytes = newArray;
		}
	}
}
